Roll insensitive air bearing slider

ABSTRACT

An air bearing slider for use in carrying a transducer adjacent a recording medium exhibits reduced sensitivity to variations in roll, crown, and skew. In one embodiment, the slider comprises an air bearing slider having a pair of substantially coplanar side rails disposed along the sides of the air bearing surface so as to form a recessed section between the side rails. The recessed section is open at both the leading and trailing ends of the slider while each side rail has a tapered section or etched step at the leading edge of the slider. One rail carries the transducer and extends for the entire length of the slider body. The rail without a transducer extends from the leading edge toward the trailing edge, but does not extend all the way to the trailing edge. Under some skew, accessing, and crash stop impact conditions, the resulting slider roll causes the flying height of the inactive rail to drop. By proper selection of the length and width of the inactive rail, the roll is biased such that the fly height of the inactive rail remains higher than that of the active rail even under worst case conditions. Therefore, minimum slider to disk spacing is larger than it would be for a slider design in which all rails extend the entire length of the slider.

TECHNICAL FIELD

This invention relates generally to air bearing sliders for use withrecording media and, more particularly, to a slider having reducedsensitivity to variations in the roll, skew, and crown of the slider.

BACKGROUND

Conventional magnetic disk drives are information storage devices whichutilize at least one rotatable magnetic media disk with concentric datatracks, a read/write transducer for reading and writing data on thevarious tracks, an air bearing slider for holding the transduceradjacent to the track generally in a flying mode above the media, asuspension for resiliently holding the slider and the transducer overthe data tracks, and a positioning actuator connected to the suspensionfor moving the transducer across the media to the desired data track andmaintaining the transducer over the data track during a read or a writeoperation.

In magnetic recording technology, it is continually desired to improvethe areal density at which information can be recorded and reliablyread. Because the recording density of a magnetic disk drive is limitedby the distance between the transducer and the magnetic media, a goal ofair bearing slider design is to "fly" a slider as closely as possible toa magnetic medium while avoiding physical impact with the medium.Smaller spacings, or "fly heights", are desired so that the transducercan distinguish between the magnetic fields emanating from closelyspaced regions on the disk.

In addition to achieving a small average spacing between the disk andthe transducer, it is essential that a slider fly at a relativelyconstant height despite the large variety of conditions it experiencesduring the normal operation of a disk drive. If the flying height is notconstant, the data transfer between the transducer and the recordingmedium may be adversely affected. It is also essential that variationsin the physical characteristics of the slider, due to manufacturingtolerances, not substantially alter the flying height of the slider. Ifthis result is not achieved, the slider's nominal fly height must beincreased to compensate for variations between sliders.

An example of a parameter that can vary during normal operation of adisk drive is the radial position of a slider with respect to therotating disk. The flying height of a slider is affected as the actuatorarm is moved radially to access different data tracks. This is due todifferences in the linear velocity of the disk at differing radii. Ineffect, the air bearing slider flies at different speeds at differingradii. Because a slider typically flies higher as velocity increases,there is a tendency for sliders to fly higher at the outer diameter ofthe disk. Disk drives and sliders must be designed to minimize thiseffect.

A slider also experiences changes in flying height due to variations inskew. Skew is a measure of the angle formed between the longitudinalaxis of the slider and the direction of disk rotation as measured in aplane parallel to the disk. Skew varies in a rotary actuator disk driveas the suspension and attached slider move in an arcuate path across thedisk. Skew also varies, to a lesser degree, in a linear actuator diskdrive when a resiliently mounted slider moves in response to forcesexerted upon it. In addition, skew is a concern due to manufacturingtolerances that may cause a slider to be mounted with a permanent,non-zero skew. For sliders mounted to either type of actuator, non-zeroskew values result in a slider being pressurized at a reduced value andtherefore flying lower. For this reason, it is important that a sliderbe relatively insensitive to variations in skew.

A slider also experiences fly height variations due to roll. For aslider with zero skew relative to disk rotation, roll is a measure ofthe angle formed between the surface of the disk and a plane holding thelongitudinal and latitudinal axes of the slider. Variations in rolloccur when a resiliently mounted slider experiences a skewed air flow orthe actuator experiences a crash stop impact. Insensitivity to rollvariations is a crucial requirement of air bearing sliders.

Variations in the crown of a slider can also lead to variations in flyheight. Crown is a measure of the concave or convex bending of theslider along its longitudinal axis. Crown develops in sliders because ofsurface stresses that arise during the fabrication and suspensionbonding processes. These stresses are not well controlled and thereforelead to sliders with relatively large variations in crown. Also, anindividual slider can experience variations in its crown due totemperature variations that occur during the normal operation of arecording disk drive. For these reasons, it is important that the flyingheight of a slider not vary substantially as a result of variations incrown. Furthermore, a slider with a non-zero crown is the equivalent ofa flat slider flying over a disk having small amplitude, long wavelengthundulations. Therefore, since all disks have some degree of waviness, aslider that is less sensitive to variations in crown is also lesssensitive to imperfections in the flatness of the recording disk it isflying over.

Finally, a slider experiences varying conditions during the high speedradial movement of the actuator as it accesses data on various portionsof the disk. High speed movement across the disk can lead to largevalues of slider roll and skew and a resultant variation in fly height.This is yet another reason that a slider must be insensitive to changesin roll and skew.

When any of the above described variations in fly height occur, they mayresult in contact between the slider and the rapidly rotating recordingmedium. Any such contact leads to wear of the slider and the recordingsurface and is potentially catastrophic. Prior art slider designs haveattempted to avoid this problem by addressing one or more of abovedescribed sensitivities, so as to produce a slider with uniform flyingheight under the varying conditions that may be experienced by theslider.

For example, U.S. Pat. No. 4,894,740 to Chhabra et al. addresses theproblem of roll sensitivity by placing a transducing element on thecenter rail of a three rail slider. This solution, while effective, hasthe disadvantage of moving the transducing element away from the edge ofthe slider. Therefore, because a slider only flies correctly when it ismore than a certain minimum distance from the outer edge of a rotatingdisk, those areas of the disk from the center of the slider to the edgeof the slider cannot be used. This can result in a loss of 2 to 4% ofthe usable storage capability of the disk.

Another approach is disclosed in U.S. Pat. No. 4,870,519 to White. Whiteaddresses the problem of roll and skew sensitivity by attempting todesign a slider that is subjected to very little roll under varying skewconditions. The solution proposed by White requires a well-controlledcontour to be placed along corresponding edges of a slider's side rails.These contours can present manufacturing difficulties because theyrequire a controlled etch depth in addition to the traditional processused to create the recess between the rails.

For the foregoing reasons, there is a need for an air bearing sliderthat maintains a relatively uniform flying height; can accommodate atransducer near its side edge; is insensitive to variations in roll,skew and crown; and does not require additional features thatsubstantially add to the difficulty of manufacturing the slider.

SUMMARY OF THE INVENTION

The present invention is directed to an air bearing slider thatsatisfies this need by reducing the length of one side rail whilebiasing the roll and pitch of the slider to ensure that the railcarrying the transducing element remains the lowest rail. Reducing thelength of the rail is characterized as removing a portion of the rail orrecessing a portion of the rail from the original rail plane. In oneembodiment, the invention comprises an air bearing slider having a pairof substantially coplanar side rails disposed along the sides of the airbearing surface so as to form a recessed section between the side rails.The recessed section is open at both the leading and trailing ends ofthe slider. In addition, each side rail has a tapered section or etchedstep at the leading edge of the slider. One rail carries the transducerand is referred to as the active rail. The active rail extends for theentire length of the slider body from the leading edge to the trailingedge. The rail without a transducer is referred to as the inactive railand extends from the leading edge toward the trailing edge, but does notextend all the way to the trailing edge. Under some skew, accessing, andcrash stop impact conditions, the resulting slider roll causes theflying height of the inactive rail to drop. By proper selection of thelength and width of the inactive rail, the roll can be biased such thatthe fly height of the inactive rail remains higher than that of theactive rail even under worst case conditions. Therefore, the active railalways remains the lowest flying rail and the minimum slider to diskspacing is larger than it would be for a standard slider design. Inaddition, the shortened rail and biased roll provide reduced sensitivityto variations in crown and skew.

In a second embodiment, the slider has a continuously tapered cross-railor etched step along the entire front edge thereof and a pair of siderails. The area between the two rails is recessed to provide a region ofsubambient or negative pressure. As in the first embodiment, theinactive rail is shortened to provide roll, crown, and sinewinsensitivity.

In a third and fourth embodiment, a channel is formed near the trailingend of the active rail of the first and second embodiments respectively.By combining a short inactive rail with a channel in the active rail,low flying heights at low gram loads can be achieved with the inactiverail always flying higher than the active rail.

This invention thus provides an air bearing slider with reducedsensitivity to variations in roll, skew, and crown while maintaining auniform flying height above a recording disk. Further features andadvantages of the invention will become apparent from the followingspecification and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a disk drive system useful forpracticing the present invention;

FIG. 2 is a top view of a magnetic recording mechanism with a rotaryactuator useful in practicing the present invention;

FIG. 3A is a bottom plan view of an air bearing slider embodying thepresent invention;

FIG. 3B is a side plan view of the air bearing slider of FIG. 3A;

FIG. 3C is another embodiment of the air bearing slider of FIG. 3Ahaving an etched step at the leading edge;

FIG. 4 is a graph illustrating the relationship between flying heightand radial disk position for the embodiment of the invention illustratedin FIG. 3A;

FIG. 5 is a bottom plan view of a negative pressure air bearing sliderembodying the present invention;

FIG. 6 is a bottom plan view of the slider of FIG. 3A with a channelpassing through the active rail;

FIG. 7 is an embodiment of the invention having shaped rails; and

FIG. 8 is a bottom plan view of a preferred embodiment of the inventionhaving two negative pressure regions and shaped rails.

FIG. 9 is a graph illustrating the relationship between flying heightand radial disk position for the embodiment of the invention illustratedin FIG. 8;

DETAILED DESCRIPTION

With reference to FIG. 1, a schematic diagram of a magnetic recordingdisk drive useful for practicing the present invention is illustratedand is designated by the general reference number 10. System 10comprises a disk spindle assembly 12 and a head actuator assembly 14.Spindle assembly 12 and head actuator assembly 14 are located within asealed housing 16 to prevent particulate contamination. Spindle assembly12 comprises a plurality of magnetic recording disks 20 which aremounted to a spindle 22. Spindle 22 is rotated by an in-hub electricalmotor which is not illustrated. Head actuator assembly 14 comprises avoice coil motor 30 which moves an actuator arm assembly 32 relative tothe disks 20. Assembly 32 has a plurality of actuator arms 34, each ofwhich is positioned in a space between two adjacent disks 20. Eachactuator arm 34 has a pair of air bearing sliders 36 adapted forcarrying read/write transducers adjacent to the disks 20. One read/writetransducer flies adjacent to the disk positioned above the actuator arm34 and the other flies adjacent to the disk positioned below theactuator arm 34.

In operation, spindle 22 is rotated by the in-hub motor and motor 30moves the actuator arms 34 between the disks 20 to the desired tracklocation. One of the read/write transducers attached to sliders 36 thenreads or writes data on the desired track.

Referring now to FIG. 2, a data recording disk drive useful forpracticing the present invention is illustrated. The disk drive includesa housing 40 in which is mounted a rotary actuator 42, an associateddisk 44 and a drive means 46 for rotating the disk 44. The rotaryactuator 42 moves a suspension assembly 48 in an arcuate path over thedisk 44. The rotary actuator 42 includes a voice coil motor, whichcomprises a coil 50 movable within the magnetic field of a fixedpermanent magnet assembly 52. An actuator arm 54 is attached to themovable coil 50. The other end of the actuator arm 54 is attached to asuspension assembly 48 which holds an air bearing slider and itsattached read/write transducer in a flying relationship adjacent to disk44.

With reference to FIGS. 3A, 3B and 3C, the air bearing surface of amagnetic head slider 60, made in accordance with the present invention,is formed with two side rails 62 and 64. The inner sides of the tworails border a recessed section 68 that is formed by etching, laserablation, ion milling, or other techniques as are known in the art. Therecessed section 68 extends from the leading edge 70 to the trailingedge 72. Transducer 74 is bonded to or integrally formed at the trailingedge of the active rail 64. The side rails 62 and 64 each have a taperedsection 66, illustrated in FIG. 3B, at the leading edge 70.Alternatively, section 66 could be an etched step, as illustrated inFIG. 3C, formed by one of the techniques applicable to recessed section68. In general, etched steps are the functional equivalent of taperedsections for all embodiments of the present invention.

The active rail 64 extends from the tapered section 66 to the trailingedge 72 of the slider 60. The inactive rail 62 extends from the taperedsection 66 toward the trailing edge 72 but does not extend the entirelength of the slider 60.

The inactive rail 62 is illustrated as having a rectangular terminationedge 63 but this is not a requirement of the present invention.Termination edge 63 may be slanted with respect to the longitudinal axisof the slider; may have a slight radius as a result of machiningoperations; or may have other shapes without seriously affecting theperformance of the present invention. Similarly, the width of rail 62 isillustrated as being identical to inactive rail 64 but, for manyapplications, would be wider so as to provide a lift roughly equivalentto that of the full length rail 64.

The following dimensions for the elements of slider 60 are illustrativeonly and not meant to limit the scope of the present invention. Theslider 60 has a width of 1.5 mm, a length of 2.045 mm and a rail widthof 0.254 mm. The tapered section 66 extends 0.320 mm in from the leadingedge 70 and the inactive rail 62 has a length of 1.5 mm. As is known inthe art, all of the preceding dimensions can be varied to meet an arrayof design requirements without departing from the scope of the presentinvention.

The length and width of inactive rail 62 is determined by trading offseveral parameters, the three most important of which are flying heightvariation, crown sensitivity, and roll bias. For example, as will beexplained in further detail below, if the rail 62 is shortened, thesensitivity of the slider 60 to crown variations is reduced while theroll bias of the slider 60 is increased. If the roll bias becomes toolarge, one of the rails may impact the disk. For most applications, theinactive rail 62 would have a length greater than 30% and less than 97%of the slider 60 body length. However, as would be apparent to oneskilled in the art, sliders with an inactive rail length greater than97% would still provide to a lesser extent the advantages of the presentinvention. Similarly, inactive rail lengths under 30% may be preferredfor certain applications and would fall within the scope of the presentinvention.

It should be noted that because all the edges of the present embodimentare linear, the slider 60 of FIG. 3A can be manufactured using low costmachining operations without the need for expensive photolithographic oretching steps. This can be a major advantage when low cost is a primarydesign goal.

In operation, slider 60 is held adjacent to a rotating disk by aresilient suspension assembly. Air flowing beneath the rails 62 and 64and recessed section 68 forms a hydrodynamic air bearing that causes theslider 60 to lift-off from the disk surface. The leading edge 70 of theslider 60 flies farther from the disk than trailing edge 72, resultingin the slider 60 flying at a pitch angle with respect to the surface ofthe disk.

The configuration of the slider 60 results in a much flatter fly heightprofile than a prior art slider of similar size and shape having twofull length rails. This is illustrated in FIG. 4, which is a graphillustrating the variation in fly height at varying disk radii for theslider of FIG. 3A as compared to a slider with full length rails. FIG. 4was generated using a computer model of the air bearing characteristicsof each slider flying over a disk. Both sliders are assumed to bemounted in a rotary actuator drive having approximately zero skew at theinner diameter and a minimum spacing of approximately 3 microinches. Ascan be seen from the graph, the slider embodying the present inventionhas a much smaller variation in fly height when compared to anequivalent slider having full length rails. It should be noted that thevariations in fly height indicated in FIG. 4 are due not just tovariations in the velocity of the disk but also to variations in skew asthe rotary actuator moves the slider across a 3.5 inch disk.

The previously described embodiment of the invention has many advantagesin addition to its reduced sensitivity to skew and radial position. Onesuch advantage is the reduced sensitivity of the present invention tovariations in the crown of the slider. As mentioned above, manufacturingtolerances lead to relatively large variations in slider crown. A keyadvantage of the present invention is the relatively small effect thatsuch variations have on the flying height of the slider. This can beunderstood by examining the variations in fly height between a sliderhaving full length rails and a slider made in accordance with thepresent invention. Assuming both sliders have a crown that changes suchthat the leading edge 70 and the trailing edge 72 move toward the disk,the slider with full length rails experiences a decrease in pressureunder each rail and therefore, flies lower. The present inventionlessens this effect in the following manner. Because the surface areaunder the inactive rail 62 is reduced, the effect of any crown variationis heightened and the rail 62 experiences a greater reduction in thelifting force generated by the rail. This causes the slider 60 to rollsuch that the active rail 64 rolls upward. This effect partiallycompensates for the pressure drop under active rail 64 caused by thecrown and results in transducer 74 experiencing a much smaller change infly height. The fact that inactive rail 62 experiences a larger dropthan it might otherwise is not a concern. Because the slider flies at apitch angle and the rail 62 is shortened, the portion of slider 60closest to the disk continues to be the area near transducer 74.

Another advantage of the present invention is better dynamic performanceof the slider 60 during data accessing. FIG. 4 illustrates the steadystate flying height of the transducer 74 at various radii. However,slider fly heights are also affected during the movement of the actuatorfrom one radial position to another. During the actuator's motion, theslider is subjected to an additional skew which can cause the slider flyheight to drop. In addition, the large skew exerts a force on the sliderthat tends to give it a large roll. Because of the above describedinsensitivity of the present invention to changes in roll or skew, theflying height of the slider 60 experiences much less of a drop in flyingheight as compared to a full length rail slider. Computer simulationsindicate that the slider of FIG. 3A would experience a drop of 16 nm inmoving from the inner diameter (ID) to the outer diameter (OD) of thedisk at 1.5 meters/sec. A similar slider having two full length railswould experience a drop of 26 nm during the same data access movement.

With reference to FIG. 5, a negative pressure straight rail air bearingis illustrated embodying the present invention. The slider 60 is formedwith two side rails 62 and 64. In addition, a tapered cross rail 65extends across the entire width of the slider 60. Alternatively, crossrail 65 could have an etched step, similar to the one illustrated inFIG. 3C, formed by one of the techniques applicable to recessed section68. The cross rail 65 and the inner sides of the two rails 62 and 64border on a recessed section 68 that is formed by etching, laserablation, ion milling or other techniques as are known in the art. Inoperation, the recessed section 68 forms a pocket of subambient ornegative pressure which reduces the requirement of high static loadingon the slider. Unlike the recessed section of the previous embodiment,the depth of the recessed section 68 of the present embodiment must beof a controlled depth, typically several microns, to achieve the properflying characteristics. As in the positive pressure embodiment, atransducer 74 is bonded to or integrally formed at the trailing edge ofthe active rail 64. The active rail 64 extends from the cross rail 65 tothe trailing edge 72 of the slider 60. The inactive rail 62 extends fromthe tapered section 66 toward the trailing edge 72 but does not extendthe entire length of the slider 60.

The configuration of the slider 60 of FIG. 5 results in a much flatterfly height profile than a prior art slider of identical size and shapehaving two full length rails. In addition, the advantages mentionedabove with respect to the embodiment of FIG. 3A apply to the slider ofFIG. 5 and all later described embodiments.

In addition to the benefits of the embodiment illustrated in FIG. 3A,the negative pressure embodiment of FIG. 5 allows the slider 60 to beused with a lower static load. Lower static loads are desirable becausethey lessen the likelihood of disk wear or damage during the slidingcontact that occurs when disk rotation is initiated. In addition, lowerstatic loads reduce the stiction forces between the slider and the mediaat zero velocity. Overcoming these forces can wear or damage the diskand the slider assembly.

With reference to FIG. 6, another embodiment of the present invention,similar to that of FIG. 3A, is illustrated. The embodiment of FIG. 6 isidentical to that of FIG. 3A with the addition of a channel 80 in theactive rail 64. For manufacturing ease, the leading edge 81 of channel80 may be aligned with the termination edge 63 of the inactive rail 62so that channel 80 and rail 62 may be machined in the same operation. Inaddition to the benefits of the embodiment illustrated in FIG. 3A, thechannel 80 allows the slider 60 to be used with a lower static load.Lower static loads are desirable for the reasons discussed above withrespect to the negative pressure embodiment of FIG. 5. Although depictedon a single embodiment, the channel 80 could be beneficially applied toall other embodiments of the present invention.

It should be noted that while channel 80 provides another degree ofdesign flexibility, it decreases the stiffness of the air bearing thatis formed between the slider 60 and the disk. For this reason, thechannel 80 would typically be used on slider air bearing surfaces formedby machining processes. If the air bearing surface is formed bypatterning techniques, such as photolithography, the advantages of slot80 can be achieved by other means without sacrificing air bearingstiffness.

With reference to FIG. 7, a positive pressure air bearing slider isillustrated. The embodiment of FIG. 7 is similar to that of FIG. 3A withthe addition of shaping near the leading edge of each rail and thetrailing end of the active rail 64. The shaping takes the form of flaredsections 91, 92 and 93. Patterning processes, such as photolithography,are required to shape the rails in this manner. Shaping of the railsprovides additional flexibility to the slider design. For example, theflared section 93, near the trailing end of active rail 64, allows theactive rail to carry a large transducing element 74 without requiringthe entire rail 64 to be wide enough to accommodate the transducer.Similarly, the flaring at sections 91 and 92 increases the pitch atwhich the slider 60 flies. Shaping, such as that illustrated in FIG. 7,could be beneficially applied to all the air bearing surfaces of allembodiments of the present invention.

With reference to FIG. 8, a preferred embodiment of the presentinvention is illustrated. The slider 60 is formed with two side rails 62and 64. The side rails 62 and 64 each have a tapered section, 66A and66B respectively, at the leading edge 70. The tapered sections 66A and66B and the inner sides of the two rails 62 and 64 border on recessedsections 68A and 68B which are formed by etching, ion milling or othertechniques. In operation, the recessed sections 68A and 68B form twopockets of negative pressure which reduce the requirement of high staticloading on the slider 60. A channel 94 passes between two sub-rails, 97Aand 97B, that extend from the tapered sections 66A and 66B respectivelytoward the trailing edge 72. A transducer 74 is bonded to or integrallyformed on the trailing edge of the active rail 64. The inactive rail 62extends from the tapered section 66A toward the trailing edge 72, butdoes not extend the entire length of the slider 60. The active rail 64extends from the tapered section 66B to the trailing edge 72 of theslider 60.

The following dimensions for the elements of slider 60 are illustrativeonly and not meant to limit the scope of the present invention. Theslider 60 has a width of 1.5 mm, a length of 2.045 mm, a rail width of0.221 mm for the active rail 64, and a rail width of 0.311 for theinactive rail 62. The tapered sections 66A and 66B extend 0.320 mm infrom the leading edge 70 and the inactive rail 62 has a length of 1.7mm. The sub-rails 97A and 97B begin 0.470 mm from leading edge 70, havea length of 0.530 mm and a width of 0.1 mm. Finally, the flare 96 on thetrailing end of active rail 64 begins 1.2 mm from the leading edge 70and extends for 0.3 mm before reaching a width of 0.5 mm. As is known inthe art, all of the preceding dimensions can be varied to meet an arrayof design requirements without departing from the scope of the presentinvention.

As illustrated in FIG. 8 and apparent from the above dimensions, thepreferred embodiment is asymmetric with inactive rail 62 being widerthan active rail 64. This more than compensates for the decreasedsurface area and therefore decreased lift of the inactive rail 62. Thisresults in a roll bias that tilts the inactive rail away from the disk.It should be noted that the asymmetry of the preferred embodimentrequires a mirror image version of the slider illustrated in FIG. 8 tobe used on the opposite side of a magnetic disk.

The configuration of the slider 60 results in a much flatter fly heightprofile than a slider of similar size and shape having two full lengthrails. This is illustrated in FIG. 9 which displays the results of acomputer simulation similar to that used to generate FIG. 4. FIG. 9illustrates the effect on slider fly height of relative disk velocityand actuator skew. As can be seen from the graph, the slider embodyingthe present invention has a much smaller variation in fly height whencompared to a similar slider having a full length inactive rail.

Although the present invention has been described in considerable detailwith reference to certain preferred versions thereof, other versions arepossible. For example, although the invention has been described in thecontext of sliders having leading edge compression features, such astapered sections or etched steps, the advantages of the presentinvention apply to sliders not having these features. Similarly,although the inactive rail of the preferred embodiments is illustratedas being completely removed from the trailing end of the slider, thebenefits of the present invention could also be achieved by simplyrecessing the trailing end of the inactive rail so as to reduce thepressurization at that point and lessen the likelihood of impact withthe disk. It should be apparent that other modifications and adaptationsof the described embodiments may occur to one skilled in the art withoutdeparting from the scope of the present invention as set forth in thefollowing claims.

We claim:
 1. An air bearing slider for supporting a transducercomprising:a slider body having a leading edge and a trailing edge; afirst negative pressure pocket defined by a first U-shaped rail, saidU-shaped rail including a cross rail extending along a first portion ofsaid leading edge, and first and second leg rails extending from saidcross rail in the direction of said trailing edge, said first leg railhaving a recessed area of reduced load bearing capability at saidtrailing edge; a second negative pressure pocket defined by a secondU-shaped rail including a cross rail extending along a second portion ofsaid leading edge, and first and second leg rails extending from saidcross rail in the direction of said trailing edge, said second legextending to said trailing edge; and a channel extending from saidleading edge toward said trailing edge, said channel interposed betweensaid first U-shaped rail and said second U-shaped rail.
 2. The slider ofclaim 1, wherein each of said cross rails of said first and secondU-shaped rails includes a compression-feature at said leading edge. 3.The slider of claim 1, wherein said first leg rail of said firstU-shaped rail includes a flared portion at said recessed area.
 4. Theslider of claim 1, wherein said first leg rail of said first U-shapedrail includes a flared portion at said recessed area, and wherein saidsecond leg rail of said second U-shaped rail includes a flared portionat said trailing edge.
 5. The slider of claim 1, wherein said first legrail of said first U-shaped rail extends along a longitudinal side edgeof said slider, and wherein said second leg rail of said second U-shapedrail extends along the other longitudinal side edge of said slider.